Vacuum valve with position sensor

ABSTRACT

Disclosed is a vacuum valve having a valve closure and having a drive unit which is coupled to the valve closure and which has at least one adjustment element. The vacuum valve furthermore has a position sensor, in particular a travel or distance sensor, such that a position of the valve closure and/or of the at least one adjustment element relative to a zero position, in particular an open position or closed position of the vacuum valve, can be measured.

This application is a continuation application of U.S. application Ser.No. 16/627,152; which is a 371 National Phase of PCT Application No.PCT/EP2018/067466, filed on Jun. 28, 2018; which claims priority toEuropean Patent application 17179066.0 filed Jun. 30, 2017 and each ofwhich is herein incorporated by reference in its entirety.

The invention relates to a vacuum valve having at least one positionsensor and a method for controlling a vacuum valve using a positionmeasurement.

Vacuum valves for regulating a volume or mass flow and/or foressentially gas-tight closing of a flow path leading through an openingformed in a valve housing are generally known from the prior art invarious embodiments and are used in particular in vacuum chamber systemsin the area of IC, semiconductor or substrate production, which musttake place in a protected atmosphere as far as possible without thepresence of contaminating particles. Such vacuum chamber systemscomprise in particular at least one evacuatable vacuum chamber which isprovided for receiving semiconductor elements or substrates to beprocessed or produced and which has at least one vacuum chamber openingthrough which the semiconductor elements or other substrates can beguided into and out of the vacuum chamber, and at least one vacuum pumpfor evacuating the vacuum chamber. For example, in a production plantfor semiconductor wafers or liquid crystal substrates, the highlysensitive semiconductor or liquid crystal elements pass sequentiallythrough several process vacuum chambers in which the parts locatedwithin the process vacuum chambers are each processed by means of aprocessing device. Both during the machining process within the processvacuum chambers and during the transport from chamber to chamber, thehighly sensitive semiconductor elements or substrates must always be ina protected atmosphere—especially in an airless environment.

For this purpose, peripheral valves are used to open and close a gasinlet or outlet and transfer valves are used to open and close thetransfer openings of the vacuum chambers for inserting and removing theparts.

The vacuum valves through which semiconductor parts pass are referred toas vacuum transfer valves due to the area of application described andthe associated dimensioning, as rectangular valves due to their mainlyrectangular opening cross-section and also as slide valves, rectangularsliders, or transfer slide valves due to their normal mode of operation.

Peripheral valves are used in particular to control or regulate the gasflow between a vacuum chamber and a vacuum pump or another vacuumchamber. For example, peripheral valves are located within a pipe systembetween a process vacuum chamber or a transfer chamber and a vacuumpump, the atmosphere, or another process vacuum chamber. The openingcross-section of such valves, also known as pump valves, is generallysmaller than that of a vacuum transfer valve. Peripheral valves are alsocalled control valves because, depending on the application, they arenot only used to completely open and close an opening, but also tocontrol or regulate a flow by continuously adjusting the openingcross-section between a complete open position and a gas-tight closedposition. A possible peripheral valve for controlling or regulating thegas flow is the pendulum valve.

In a typical pendulum valve, as known from U.S. Pat. No. 6,089,537(Olmsted), the first step is to rotate a normally round valve plate froma position that releases the opening, the open position, to anintermediate position that covers the opening via an opening that isusually also round. In the case of a slide valve, as described forexample in U.S. Pat. No. 6,416,037 (Geiser) or U.S. Pat. No. 6,056,266(Blecha), the valve plate, as well as the opening, is usuallyrectangular and in this first step is pushed linearly from a positionreleasing the opening into an intermediate position covering theopening. In this intermediate position, the valve plate of the pendulumor slide valve is located at a distance from and opposite to the valveseat surrounding the opening. In a second step, the distance between thevalve plate and the valve seat is reduced so that the valve plate andthe valve seat are pressed evenly against each other, so that the valveclosure reaches a closed position and the opening is closed essentiallygas-tight. This second movement preferably occurs in a directionsubstantially perpendicular to the valve seat.

The respective end position of an adjustment movement, i.e., the openposition and the closed position (and if an adjustment movement made oftwo combined partial movements in at least two different adjustmentdirections is provided, also the intermediate position) is detectedand/or maintained in this case using mechanical end position switches.Narrow tolerance limits are disadvantageously to be maintained for thispurpose for an exact closure.

The sealing can either take place via a sealing ring arranged on theclosure side of the valve plate, which is pressed onto the valve seatcircumferential around the opening, or via a sealing ring on the valveseat, against which the closure side of the valve plate is pressed. Dueto the closing procedure occurring in two steps, the sealing ringbetween the valve plate and the valve seat is hardly subjected to shearforces, which would destroy the sealing ring, since the movement of thevalve plate in the second step takes place essentially linearlyperpendicularly onto the valve seat.

Various prior art sealing devices are known, for example from the U.S.Pat. No. 6,629,682 B2 (Duelli). A suitable material for sealing ringsand seals in vacuum valves is, for example, fluoro rubber, also known asFKM, in particular the fluoroelastomer known under the trade name“Viton”, and perfluororubber, FFKM for short.

From the prior art, different drive systems are known to achieve arotational movement of the valve plate of the pendulum valve and atranslational movement of the valve plate of the slide valve parallel tothe opening and a substantially translational movement perpendicular tothe opening, for example from U.S. Pat. No. 6,089,537 (Olmsted) for apendulum valve and from U.S. Pat. No. 6,416,037 (Geiser) for a slidevalve.

The valve plate must be pressed against the valve seat in such a waythat both the required gas tightness within the entire pressure range isensured and damage to the sealing medium, in particular the sealing ringin the form of an O-ring, caused by excessive pressure loading isavoided. In order to guarantee this, well-known valves provide forpressure regulation of the valve plate which is regulated depending onthe pressure difference prevailing between the two valve plate sides.Especially with large pressure fluctuations or the change from partialvacuum to overpressure, or vice versa, an even force distribution alongthe entire circumference of the sealing ring cannot always beguaranteed. In general, the aim is to decouple the sealing ring fromsupport forces resulting from the pressure applied to the valve. In theU.S. Pat. No. 6,629,682 (Duelli), for example, a vacuum valve with asealing medium is proposed, which consists of a sealing ring and anadjacent support ring, so that the sealing ring is essentially free ofsupport forces.

In order to achieve the required gas tightness, possibly for bothoverpressure and partial vacuum, some well-known pendulum valves orslide valves additionally or alternatively to the second movement stepprovide a valve ring which can be displaced perpendicularly to the valveplate, surrounds the opening, and is pressed onto the valve plate toclose the valve in a gas-tight manner. Such valves with valve rings thatcan be actively displaced relative to the valve plate are known, forexample, from DE 1 264 191 B1, DE 34 47 008 C2, U.S. Pat. No. 3,145,969(von Zweck) and DE 77 31 993 U. U.S. Pat. No. 5,577,707 (Brida)describes a pendulum valve with a valve housing having an opening and avalve plate that swivels parallel across the opening to control flowthrough the opening. A valve ring which surrounds the opening can beactively moved vertically in the direction of the valve plate by meansof several springs and compressed air cylinders. A possible furtherdevelopment of this pendulum valve is proposed in US 2005/0067603 A1(Lucas et al.).

Since the valves mentioned above are used, among other things, in theproduction of highly sensitive semiconductor elements in a vacuumchamber, a corresponding sealing effect must also be reliably guaranteedfor such process chambers. For this purpose, in particular the conditionof a sealing material or a sealing surface in contact with the sealingmaterial during compression is of particular importance. During theservice life of a vacuum valve, wear of the sealing material or thesealing surfaces can typically occur.

Furthermore, the drive system and/or the mechanically moving componentsof the valve are susceptible to faults, for example, because ofappearances of wear or aging or because of external interferinginfluences such as mechanical shocks or the like, so that impairments ofthe sealing action or the function or reliability of the vacuum valve ingeneral can occur. There has heretofore been no option in the prior artto recognize such faults early and/or beforehand.

To keep the quality of the valve and/or the sealing at a sufficientlyhigh level consistently, maintenance of the valve therefore typicallytakes place at specific time intervals, frequently by replacing orrestoring parts of the valve, for example, the seal, drive parts, or thevalve as a whole. Such a maintenance cycle is usually dimensioned inthis case based on the number of the opening and closing cycles to beexpected in a certain period of time. The maintenance thus usually takesplace as a precaution to be able to preclude the occurrence of a leak orother malfunctions beforehand as much as possible.

Such a maintenance requirement is not limited to the sealing material orthe valve plate alone but extends, for example, to the valve seat, whichforms a part of the vacuum valve corresponding to the valve plate. Thestructure of a sealing surface on the side of the valve seat, e.g. agroove embedded in the valve seat, is also affected by mechanicalstress. Therefore, a structural change in the groove resulting fromvalve operation may also impair the seal. Appropriate maintenanceintervals are typically also defined for this purpose.

A disadvantage of this valve maintenance is its precautionary character.Parts affected by maintenance are usually renewed or replaced beforetheir regular or actual life expires, which means an elevated costexpenditure. Each such maintenance step usually means a certain downtimefor a production process and an increased technical and financialeffort. In sum, this means a stoppage in production at intervals thatare shorter than necessary and more frequent than would be necessary atall.

The invention is therefore based on the object of providing an improvedvacuum valve, which allows an optimized operation.

It is a further object of the invention to provide an improved vacuumvalve, which allows optimized valve maintenance and thus an improvement,i.e. a shortening of possible process stoppages.

It is a further object of the invention to provide an improved vacuumvalve which enables a lengthening of the service life of individualvalve parts.

It is a further object of the invention to provide an improved vacuumvalve, which places less strict tolerance requirements on individualcomponents and/or on the production.

These objects are solved by the realization of the characterizingfeatures of the independent claims. Features which further develop theinvention in an alternative or advantageous way can be found in thedependent patent claims.

The basic idea of the present invention is to equip a vacuum valve witha position sensor and to design the valve and the sensor arrangement insuch a way that a, preferably progressive, determination or monitoringof the position of at least one of the mechanically moved parts of thevalve is enabled.

The subject matter of the invention is thus a vacuum valve, preferably avacuum slide valve, a pendulum valve or a monovalve, for regulating avolume or mass flow and/or for gas-tight interruption of a flow path,having a valve seat which has a valve opening defining an opening axisand a first sealing surface surrounding the valve opening. The valveseat can be an integral or structural component of the vacuum valve inthis case and in particular can embody a part of the valve housing.Alternatively, the valve seat can be formed by the opening of a processchamber, for example, a vacuum chamber, and can form a vacuum valve inthe meaning of the present invention in cooperation with the valveclosure movable in relation to the valve seat.

Furthermore, the vacuum valve comprises a valve closure, in particular avalve plate, for the regulation of the volume or mass flow and/or forthe interruption of the flow path, having a second sealing surfacecorresponding to the first sealing surface, the variable location ofwhich is determined by a respective position and alignment of the valveclosure. Moreover, the vacuum valve has a drive unit coupled to thevalve closure comprising at least one movable adjustment element, forexample, an adjustment arm, wherein the drive unit is designed toexecute an adjustment movement, so that the valve closure is thusadjustable from an open position, in which the valve closure and thevalve seat are provided without contact in relation to one another, intoa closed position, in which an axially sealing contact with respect tothe opening axis exists between the first sealing surface and the secondsealing surface, in particular via a seal, and the valve opening is thusclosed gas-tight, and back again.

In particular, one or both of the two sealing surfaces has a seal madeof sealing material. The sealing material can be, for example, apolymer-based material (for example, an elastomer, in particular afluoroelastomer), which is vulcanized onto the sealing surface or isprovided as an O-ring in a groove in the valve closure or the valveseat. Sealing surfaces are thus, in the scope of the invention,preferably considered to be those surfaces in which a seal made ofsealing material is provided in compressed form to close the valveopening (closed position).

The drive unit can be designed as an electric motor (stepper motor) oras a combination of multiple motors or as a pneumatic drive. Inparticular, the drive unit provides a movement of the valve closure inat least two directions (essentially orthogonal to one another).

According to the invention, the vacuum valve has at least one positionsensor, wherein the position sensor is designed and arranged in thevacuum valve such that a position of the valve closure and/or the atleast one adjustment element, in particular an adjustment arm, ismeasurable, preferably progressively, with respect to a null position,in particular the open position or closed position.

The position sensor is preferably a displacement sensor comprising aposition-transducing element. Alternatively, the sensor is designed as adistance sensor. In the case of multiple sensors, both types can also beused. The position sensor is preferably designed as an absolute positionsensor, and therefore positions are determinable without approaching thenull position, for example, by means of a unique position code on aruler, a material measure, or a scale of the sensor.

The sensor is preferably designed and arranged in the vacuum valve suchthat the time curve of at least part of the adjustment movement isdeterminable. Thus, multiple positions are determined in sequence over aspecific time span, for example, such that at least one velocity of theadjustment movement or the adjustment element and/or the valve closureis determinable or derivable therefrom for at least this one time spanof the adjustment movement. In addition, accelerations can furthermorealso be determined from the position measurements.

As an option, the adjustment movement comprises an at least essentiallylinear movement and the position sensor is designed and arranged toacquire at least a part of or the entirety of the linear movement,wherein the position sensor is preferably a linear encoder.

Alternatively or additionally, the adjustment movement comprises an atleast essentially rotational movement and the position sensor isdesigned and arranged to acquire at least a part of or the entirety ofthe rotational movement, wherein the position sensor is preferably anangle encoder.

The position sensor is optionally an inductive, optical, magnetic,magnetostrictive, potentiometric, and/or capacitive position sensor. Asa further option, the position sensor is arranged outside a vacuumregion, which is defined by the vacuum valve and is separated from anexternal environment. It is thus advantageous in this case that thesensor arrangement can be designed, for example, such that the sensoritself, for example, does not have to be moved into the vacuum regionand therefore a comparatively lesser construction expenditure can beensured.

In some embodiments, the position sensor is designed and arranged in thevacuum valve such that by means of the one position sensor, a positionmeasurement can be carried out with respect to at least two adjustmentdirections, which are essentially orthogonal to one another inparticular, i.e., a single position sensor can determine positions withrespect to multiple axes or directions. This takes place, for example,in that a target of the sensor is received from multiple rulers, eithersequentially, for example, firstly upon adjustment along the firstadjustment direction and then upon adjustment along the secondadjustment direction, or simultaneously, for example, by design as a 2Dposition sensor. Alternatively, the vacuum valve has at least twoposition sensors, which are designed and arranged in the vacuum valvesuch that a position with respect to a first adjustment direction ismeasurable by means of the first position sensor and a position withrespect to a second adjustment direction is measurable by means of thesecond position sensor, in particular wherein both adjustment directionsare essentially orthogonal to one another.

In one embodiment, the vacuum valve has a monitoring and control unitfor activating the drive unit using predefined control values to adjustthe valve closure between the open position and the closed position,wherein the drive unit, the valve closure, and the sensor are designedand interact such that the control values are set based on themeasurement signal of the sensor, in particular such that themeasurement signal continuously corresponds to a predefined setpointvalue.

In this case, the vacuum valve, the sensor arrangement, and themonitoring and control unit are optionally configured, for example, suchthat the position sensor is in one-sided or two-sided communication, forexample, via a conventional wired or wireless connection, with themonitoring and control unit for provision and transmission of themeasurement signal.

The vacuum valve can furthermore have a processing unit designed suchthat, for example, in particular provided by the monitoring and controlunit or the sensor arrangement, an acquired measurement signal isprocessable by means of the processing unit and an item of stateinformation can be generated on the basis of the acquired measurementsignal. The acquired measurement signals can then be further processedand provided for the provision of an item of state information which canbe evaluated, for example, for the valve regulation by the monitoringand control unit or as user information.

The item of state information can provide, for example, an item ofinformation with respect to a mechanical and/or structural integrity ofthe valve closure and/or the adjustment element, for example, based onan actual-setpoint comparison for the acquired position measurementsignal, for example, based on an acquired and an expected position for areference (setting) position of the drive unit.

Furthermore, based on the item of state information, an output signalcan be provided, which specifies a relationship of the acquired positionsensor measurement signal to specific tolerance values. Thus, inparticular an evaluation can take place with respect to a processcontrolled by the vacuum valve, for example, an evaluation of whether arequired sealing action is achieved or possible damage, for example, tothe adjustment elements or sealing surfaces can be recognized. Forexample, it can then be indicated to a user, for example, by a visual oracoustic signal whether a process runs within the required tolerances oran undesired falling below or exceeding of such a tolerance is to beexpected (for example, based on the adjustment velocity or endlocation).

The present invention moreover comprises methods for controlling avacuum valve, in particular a vacuum slide valve, pendulum valve, ormonovalve, wherein the vacuum valve is designed for the regulation of avolume or mass flow and/or for the gas-tight interruption of a flowpath. The vacuum valve to be controlled has a valve seat in this case,which has a valve opening defining an opening axis and a first sealingsurface circumferential around the valve opening, a valve closure, inparticular a valve plate, for the regulation of the volume or mass flowand/or for the interruption of the flow path, comprising a secondsealing surface corresponding to the first sealing surface, the variablelocation of which is determined by a respective position and alignmentof the valve closure, a drive unit coupled to the valve closurecomprising at least one movable adjustment element, wherein the driveunit is designed to execute an adjustment movement, and therefore thevalve closure is adjustable from an open position, in which the valveclosure and the valve seat are provided without contact in relation toone another, into a closed position, in which, in particular via a seal,an axially sealing contact with respect to the opening axis existbetween the first sealing surface and the second sealing surface and thevalve opening is thus closed gas-tight, and back.

According to the invention, in the scope of the method, an in particularabsolute position of the valve closure and/or the at least oneadjustment element with respect to a null position, in particular theopen position or closed position, is measured, in particularprogressively.

In one refinement of the method, an item of state information of thevacuum valve, in particular with respect to a mechanical and/orstructural integrity of the valve closure or the valve element, isascertained in the scope of the method based on the positionmeasurement, wherein preferably the item of state information isascertained by means of an actual-setpoint comparison for the acquiredmeasurement signal and/or, based on a comparison of the item of stateinformation to predefined tolerance values, an output signal is providedwith respect to an evaluation of a process controlled by the vacuumvalve.

An adjustment velocity of the valve closure and/or the at least oneadjustment element is optionally determined at least for a part of theadjustment movement and/or the duration of the adjustment movement fromthe open position to the closed position and/or vice versa in the scopeof the method based on the position measurement. Such items ofinformation can be output to a user in this case in the form of adiagram for analysis and/or can be analyzed automatically.

As a further option, a detection of an end location, in particular theopen position and/or closed position, of the valve closure and/or the atleast one adjustment element and/or a possible impact of the sealingsurfaces on one another in the scope of the adjustment movement and/or apossible adhesion of the sealing surfaces on one another takes place inthe scope of the method based on the position measurement.

The subject matter of the present invention is furthermore a computerprogram product having program code which is stored on amachine-readable carrier, in particular a control and processing unit ofa vacuum valve according to the invention, or a computer data signal,embodied by an electromagnetic wave, for carrying out the methodaccording to the invention.

The present invention thus advantageously provides a vacuum valve whichenables an ongoing or continuous position measurement of the valveclosure and/or of adjustment elements, in such a way that adjustmentmovements or sequences can be monitored or checked and possiblyevaluated. Furthermore, the position measurement enables an automaticand ongoing state verification of the vacuum valve and/or individualones of its components, for example, the drive unit, of seals, or ofadjustment elements, wherein items of state information can beascertained or derived not only directly via moving components, butrather also indirectly via stationary parts. Faults or irregularitieswhich indicate future faults can only be recognized early or at all inthis case, and/or unnecessary maintenance can be avoided because a lackof faults is established. The checks can advantageously take placeduring the normal process sequences in this case, and therefore they donot have to be interrupted.

The vacuum valve according to the invention is described in more detailbelow by means of embodiment examples schematically shown in thedrawings. The same elements are marked in the figures with the samereference numerals. As a rule, the embodiments described are not toscale and are not to be understood as limitations.

The Figures Show in Detail:

FIG. 1 a, b show a possible first embodiment of a vacuum valve accordingto the invention as a monovalve;

FIG. 2 shows a possible second embodiment of a vacuum valve according tothe invention as a monovalve;

FIGS. 3 a-c show a possible further embodiment of a vacuum valveaccording to the invention as a transfer valve;

FIG. 4 a, b show a schematic illustration of a further embodimentaccording to the invention of a vacuum valve as a pendulum valve;

FIG. 5 a, b show a schematic illustration of a further embodimentaccording to the invention of a vacuum valve as a transfer valve; and

FIG. 6 a, b show a schematic illustration of a further embodimentaccording to the invention of a vacuum valve as a transfer valve.

FIGS. 1 a, 1 b schematically show a first embodiment of a vacuum valve 1according to the invention. In the example, the valve 1 is embodied as aso-called monovalve and is shown in cross-section in an open position O(FIG. 1 a ) and a closed position G (FIG. 1 b ).

The valve 1, for the gas-tight closing of a flow path by means of alinear movement, has a valve housing 24 comprising an opening 2 for theflow path, wherein the opening 2 has a geometrical opening axis H alongthe flow path. The opening 2 connects a first gas region L, which islocated in the drawing on the left of the valve 1 and/or a partitionwall (not shown), to a second gas region R on the right thereof. Such apartition wall is formed, for example, by a chamber wall of a vacuumchamber.

The closure element 4 is displaceable linearly along a geometricadjustment axis V, which extends transversely to the opening axis H, ina closure element plane 22 from an open position O, which releases theopening 2, into a closed position G, which is pushed linearly over theopening 2, in a closing direction and vice versa back in an openingdirection by means of a drive unit 7 having a movable positioningelement 5, in the example an adjustment arm.

For example, a curved first sealing surface 3 encloses the opening 2 ofthe valve housing 24 along a first section 21 a in a first plane 20 aand along a second section 21 b in a second plane 20 b. The first plane20 a and the second plane 20 b are spaced apart from one another, extendparallel to one another, and extend parallel to the closure elementplane 22. The first section 21 a and the opposing second section 21 btherefore have a geometric offset in relation to one anothertransversely to the adjustment axis V and in the direction of theopening axis H. The opening 2 is arranged between the two opposingsections 21 a and 21 b in the region extending along the adjustment axisV.

The closure element 4 has a second sealing surface 6, which extendsalong sections corresponding to the first and second sections 21 a, 21b, corresponding to the first sealing surface 3.

Monovalves, i.e., vacuum valves closable by means of a single linearmovement, have the advantage, for example, of a comparatively simpleclosing mechanism, for example, compared to the transfer valves closableby means of two movements, which require a comparatively complexlyconstructed drive. Since the closure element can moreover be formed inone piece, it can be subjected to high acceleration forces, andtherefore this valve can also be used for rapid and emergency closures.The closing and sealing can take place by means of a single linearmovement, and therefore very rapid closing and opening of the valve 1 ispossible.

In particular, one advantage of monovalves is, for example, that theseal 3, 6, because of its profile during closing, is not subjected to atransverse load in the transverse direction in relation to thelongitudinal extension of the seal 3, 6. On the other hand, the seal 3,6 is hardly capable, because of its transverse extension in relation tothe opening axis H, of absorbing forces occurring on the closure element4 along the opening axis H, which can act on the closure element 4 inparticular in the case of large differential pressure, which requires arobust construction of the closure element 4, its drive, and itsmounting.

According to the invention, the vacuum valve 1 shown in FIGS. 1 a and 1b comprises a displacement sensor 10, which in the example has aposition-transducing element (target) 8 and a sensor surface 9 (ruler)for the detection thereof. The displacement sensor 10 is designed, forexample, as a (contactless) inductive displacement sensor, for example,a differential transformer having displaceable core, a pulsed inductivelinear position sensor, PLCD displacement sensor (permanent linearcontactless displacement sensor), optoelectronic displacement sensor,potentiometric displacement sensor, magnetostrictive displacementsensor, capacitive displacement sensor, or magnetic displacement sensor.Depending on the sensor 10, the ruler 9 is active and theposition-transducing element 8 is passive or vice versa, i.e., the(electrical or electronic) measurement signal and/or analysis signal isgenerated or tapped either by the ruler 9 or element 8, respectively.

In the example, the target 8 is fastened on or in the adjustment element4, and therefore it moves with it along the adjustment axis V. Thesensor surface 9 extends in the adjustment direction V at least over theentire adjustment distance, and therefore the position of the target 8and thus the adjustment element 4 is measurable over the entire possiblelinear movement of the adjustment element 4. The position is ascertainedin this case in relation to a starting or null position, which ispreferably either the open position O or the closed position G. Thedisplacement sensor 10 is preferably an absolute encoder in this case.Alternatively, an incremental displacement sensor is used.

The actual position of the adjustment element 4 can thus advantageouslybe determined by means of the position sensor 10. The positionmeasurement can be restricted in this case to the determination of oneor a few positions, preferably the end position (i.e., open position Oand/or closed position G), for example, in the meaning of an endlocation detection. However, an ongoing or continuous positiondetermination preferably takes place, and therefore the position of theadjustment element 4 is known progressively and in particular the timecurve thereof is known.

By way of the sensor arrangement according to the invention, forexample, the closing capability of the valve can therefore be checkedduring a process sequence, the contact pressure can be regulatedaccordingly, and a failure of the leak-tightness can possibly bepredicted. In particular, for example, the compression can be setindividually using an electric drive unit 7. Using a pneumatic drive 7,it can at least be checked using the sensor arrangement whether thevalve is closed.

The knowledge of the chronological movement curve is optionally used todetermine the velocity of the linear movement of the closure element 4therefrom. This can advantageously be used for an improved end locationdetermination, whereby tolerances in the vacuum valve become lesscritical. The exact duration for the closing or opening procedure maythus also be ascertained, whereby, for example, optimizations or faultrecognition are enabled. In general, an analysis of thetime-displacement curve, which is performed, for example, by an externaldata processing system, to which the position sensor 10 and/or thevacuum valve 1 is connected, enables inferences about the state of thevalve 1. Irregularities or changes in the course of the operating cyclescan thus be recognized, and the state of the moving components or thesealing surfaces 3, 6 can thus be concluded, for example. If the twosealing surfaces 3, 6 adhere to one another in the closed position G,for example, it is thus recognizable in the movement sequence, since theposition of the adjustment element 4 remains constant for a certainlength of time because of the adhesive force, although it is driven bythe drive unit 7 via the adjustment element 5, followed by a rapidopening movement and a brief recoil.

FIG. 2 shows an alternative to the embodiment according to FIGS. 1 a, 1b . In this example, the vacuum valve 1 has a position sensor 10designed as a distance sensor. The distance sensor 10 is, for example,an optoelectronic distance sensor or an ultrasonic sensor and emits acorresponding measurement signal 13 by means of an emitter, for example,laser light, in the direction of the adjustment element 4 and/or thevertical axis V, and therefore the signal 13 is incident on theadjustment element 4 (in the example on its rear surface), is at leastpartially reflected therefrom, and is received again by a detector ofthe sensor 10. In this case, the distance between sensor 10 andadjustment element 4 and therefore the position of the adjustmentelement 4 is determined by means of determination of the signal runtime(pulse runtime method) and/or phase difference measurement, phase orfrequency runtime methods, and/or according to the Fizeau principle. Asa further option, a position determination takes place by means oftriangulation.

To improve the distance and/or position measurement, in the example, thevacuum valve 1 has a reflector 14 arranged on the adjustment element,which is designed to reflect the measurement signal 13 toward the sensor10 and thus improve the signal level of the received measurement signal13. Alternatively to the illustrated arrangement, the sensor 10 isarranged on the moving part, i.e., on the closure 4 here, and emitsmeasurement radiation 13 toward a static point of the valve 1 (i.e., aninverted arrangement from the illustration).

FIGS. 3 a-3 c show a further embodiment of a vacuum valve 1 according tothe invention, which is designed in the example as a transfer valve,illustrated in different closure positions.

The transfer valve shown is a special form of a slide valve. The vacuumvalve has a rectangular, plate-shaped closure element 4 (for example,valve plate), which has a sealing surface 6 for the gas-tight closing ofan opening 2. The opening 2 has a cross-section corresponding to theclosure element 4 and is formed in a wall 12. The opening 2 is enclosedby a valve seat, which in turn also provides a sealing surface 3corresponding to the sealing surface 6 of the closure element 4. Thesealing surface 6 of the closure element 4 is circumferential around theclosure element 4 and has a sealing material (seal). In a closedposition, the sealing surfaces 6, 3 are pressed against one another andthe sealing material is compressed at the same time.

The opening 2 connects a first gas region L, which is located on theleft of the wall 12, to a second gas region R on the right of the wall12. The wall 12 is formed, for example, by a chamber wall of a vacuumchamber. The vacuum valve 1 is then formed by an interaction of thechamber wall 12 with the closure element 4.

The closure element 4 is arranged on an adjustment arm 5, which isrod-shaped here, for example, and which extends along a geometricadjustment axis V. The adjustment arm 5 is mechanically coupled to adrive unit 7, by means of which the closure element 4 is adjustable in afirst gas region L on the left of the wall 12 by adjustment of theadjustment arm 5 by means of the drive unit 7 between an open position O(FIG. 3 a ) via an intermediate position Z (FIG. 3 b ) into a closedposition G (FIG. 3 c ).

In the open position O, the closure element 4 is located outside theprojection region of the opening 2 and releases it completely, as shownin FIG. 3 a.

By adjusting the adjustment arm 5 in the axial direction parallel to thefirst, “vertical” adjustment axis V and parallel to the wall 12, theclosure element 4 can be adjusted by means of the drive unit 7 from theopen position O into the intermediate position Z.

In this intermediate position Z (FIG. 3 b ), the sealing surface 6 ofthe closure element 4 overlaps the opening 2 and is located in aposition spaced apart opposite to the sealing surface 3 of the valveseat enclosing the opening 2.

By adjusting the adjustment arm 5 in the direction of the second“horizontal” adjustment axis H (transversely to the first adjustmentaxis V), i.e., for example, perpendicularly to the wall 12 and to thevalve seat, the closure element 4 can be adjusted from the intermediateposition Z into the closed position G (FIG. 3 c ).

In the closed position G, the closure element 4 closes the opening 2 ina gas-tight manner and separates the first gas region L from the secondgas region R in a gas-tight manner.

The opening and closing of the vacuum valve thus takes place by means ofthe drive unit 7 by way of an L-shaped movement in two directions H, Vperpendicular to one another of the closure element 4 and the adjustmentarm 5. The transfer valve shown is therefore also called an L-typevalve.

A transfer valve 1 as shown is typically provided for sealing a processvolume (vacuum chamber) and for loading and unloading the volume.Frequent changes between the open position O and the closed position Gare the rule in the case of such a use. Increased appearances of wear ofthe sealing surfaces 6, 3 and the mechanically moved components, forexample, the adjustment element 5 or other parts of the drive unit 7,can thus occur.

For early determination of such appearances of wear, among other things,the vacuum valve 1 according to the invention has a position sensor 10,which is designed in the example as a two-axis displacement sensor. Incontrast to the embodiment according to the example of FIG. 1 a, b , aposition is determined in both adjustment directions V, H by means of atarget 8 attached to the adjustment element 5. For this purpose, thevacuum valve 1 has a first “vertical” ruler 9 v for the positiondetermination of the “vertical” movement between the open position O tothe intermediate position Z and a second, “horizontal” ruler 9 h for theposition determination of the “horizontal” movement between theintermediate position Z and the closed position G. By means of thetarget 8 arranged on the adjustment element 5 and the first ruler 9 v,in sequential sequence according to the sequential movement sequenceopen position O—intermediate position Z—closed position G (or viceversa), the position of the adjustment element 5 is thus measured in thefirst, “vertical” adjustment direction V, and by means of the target 8and the second ruler 9 h, the position is measured in the second,“horizontal” adjustment direction H.

In the example, the valve 1 and/or the position sensor 10 furthermorehas a control and/or analysis unit 11, using which the positionmeasurement is controlled and/or position data are recorded or analyzed,and therefore, for example, an external computer can (substantially) bedispensed with and, for example, solely valve-internal monitoring orstate monitoring of the valve 1 takes place.

Alternatively to the illustrated sequentially arranged two linear rulers9 v, 9 h, a single 2D sensor surface is used (not shown), which isoptically scanned, for example, and therefore a simultaneousdetermination of the position of the adjustment element 5 in both axesor directions V and H is enabled.

As a further alternative, the position determination with respect to thetwo adjustment directions V, H or the two adjustment movements does nottake place by means of a single position sensor 10, but rather the valve1 has one position sensor 10 for each adjustment direction V, H oradjustment movement, and thus comprises two position sensors 10.

FIG. 4 a and FIG. 4 b schematically show a further possible embodimentof the valve according to the invention in the form of a pendulum valve1. The valve 1 for the essentially gas-tight interruption of a flow pathhas a valve housing, which has an opening 2. The opening 2 has acircular cross-section here, for example. The opening 2 is enclosed by avalve seat. This valve seat is formed by a (first) sealing surface 3,which faces axially in the direction of a valve plate 4 and extendstransversely to the opening axis H, has the shape of a circular ring,and is formed in the valve housing. The valve plate 4 is pivotablearound an axis of rotation R and is adjustable essentially parallel tothe opening axis H. In a closed position G (FIG. 4 b ) of the valveplate 4 (valve closure), the opening 2 is closed gas-tight by means ofthe valve plate 4, which has a second sealing surface 6. An openposition O of the valve plate 4 is illustrated in FIG. 4 a.

The valve plate 4 is connected via an arm 5, which is arranged laterallyon the plate and extends perpendicularly to the opening axis H, to adrive unit 7. This arm 5 is located, in the closed position G of thevalve plate 4, outside the opening cross-section of the opening 2geometrically projected along the opening axis H.

The drive 7 is designed by use of a motor and a corresponding gearingsuch that the valve plate 4—as is typical in a pendulum valve—ispivotable by means of a transverse movement x of the drive 7transversely to the opening axis H and essentially parallel over thecross-section of the opening 2 and perpendicularly to the opening axis Hin the form of a pivot movement Br around the pivot axis R between anopen position O and an intermediate position and is linearlydisplaceable by means of a longitudinal movement Bv of the drive 7occurring parallel to the opening axis 5. In the open position O, thevalve plate 4 is positioned in a dwell section arranged laterallyadjacent to the opening 2, and therefore the opening 2 and the flow pathare released. In the intermediate position, the valve plate 4 ispositioned spaced apart above the opening 2 and covers the openingcross-section of the opening 2. In the closed position, the opening 2 isclosed gas-tight and the flow path is interrupted, in that a gas-tightcontact exists between the sealing surface 6 of the valve closure 4(valve plate) and the sealing surface 3 of the valve seat.

To enable automated and regulated opening and closing of the valve 1,the valve 1 provides, for example, an electronic regulating and controlunit (not shown), which is designed and is connected to the drive 7 suchthat the valve plate 4 is adjustable accordingly for the gas-tighttermination of a process volume or for the regulation of an internalpressure of this volume.

In the present exemplary embodiment, the drive 7 is designed as anelectric motor, wherein the gearing is switchable such that driving ofthe drive 78 causes either the transverse movement Br or thelongitudinal movement Bv. The drive including gearing is electronicallyactivated by the regulator. Such gearings, in particular having slottedlink shift units, are known from the prior art. It is furthermorepossible to use multiple drives to cause the rotational movement Br andthe linear movement Bv, wherein the controller assumes the activation ofthe drives.

The precise regulation and/or setting of the flow rate using thedescribed pendulum valve 1 is possible not only by way of the pivotingadjustment of the valve plate 4 between the open position O and theintermediate position by means of the transverse movement Br, but ratherabove all by linear adjustment of the valve plate 4 along the openingaxis H and/or R between the intermediate position and the closedposition by means of the longitudinal movement Bv. The describedpendulum valve can be used for precise regulating tasks.

Both the valve plate 4 and also the valve seat each have a sealingsurface—a first and a second sealing surface 3, 6. The first sealingsurface 3 moreover has a seal 23. This seal 23 can be, for example,vulcanized as a polymer by means of vulcanization onto the valve seat.Alternatively, the seal 23 can be embodied, for example, as an O-ring ina groove of the valve seat. A sealing material can also be adhesivelybonded onto the valve seat and thus embody the seal 23. In analternative embodiment, the seal 23 can be arranged on the side of thevalve plate 4, in particular on the second sealing surface 6.Combinations of these embodiments are also conceivable. Such seals 23are of course, not restricted to the valve 1 described in the example,but rather are also applicable in the further described valveembodiments.

The valve plate 4 is variably set, for example, on the basis ofregulating variables and an output control signal. An item ofinformation about a present pressure state in a process volume connectedto the valve 1, for example, is received as an input signal. Moreover, afurther input variable, for example, a mass inflow into the volume, canbe provided to the regulator. On the basis of these variables and on thebasis of a predefined setpoint pressure, which is to be set or achievedfor the volume, a regulated setting of the valve 1 then takes place overthe time of a regulating cycle, and therefore a mass outflow out of thevolume can be regulated over time by means of the valve 1. For thispurpose, a vacuum pump is provided behind the valve 1, i.e., the valve 1is arranged between the process chamber and the pump. A desired pressurecurve can thus be modulated.

A respective opening cross-section for the valve opening 2 is set by thesetting of the valve closure 4 and thus the possible gas quantity is setwhich can be evacuated per unit of time out of the process volume. Thevalve closure 4 can have a shape deviating from a circular shape forthis purpose, in particular to achieve the most laminar possible mediaflow.

To set the opening cross-section, the valve plate 4 is adjustable by theregulating and control unit by means of the transverse movement Br ofthe drive 7 from the open position O into the intermediate position andby means of the longitudinal movement Bv of the drive 7 from theintermediate position into the closed position. To completely open theflow path, the valve plate 4 is adjustable by the controller by means ofthe longitudinal movement Bv of the drive 7 from the closed position Ginto the intermediate position and therefrom by means of the rotationalmovement Br of the drive 7 from the intermediate position into the openposition O.

The pressing of the valve plate 4 onto the valve seat has to take placesuch that both the required gas-tightness is ensured within the entirepressure range, and also damage to the valve 1, or more precisely thesealing surfaces 3, 6 or the seal(s) 23 due to excessively largepressure strain is avoided. To ensure this, known valve plates provide acontact pressure regulation of the valve plate 4 regulated as a functionof the pressure difference prevailing between the two valve plate sides.

According to the invention, the valve 1 has two position sensors 10 and10′, designed in the example as linear encoder 10 and angle encoder 10′.

The linear position sensor 10 has a scale 9, which extends on the arm 5along the linear movement direction Bv on the arm 5 and is thereforemovable in the feed direction Bv in relation to the stationary part ofthe valve 1, i.e., for example, in relation to the valve housing or thedrive unit 7. The respective relative position is ascertained by thelinear encoder by means of a read head 8, which scans the scale 9, whichhas a position code for this purpose. The scale 9 and/or the read headare formed at least partially “wide” in this case such that a linearposition is also measurable in different rotational positions of the arm5. The scale 9 thus extends, for example, far enough around the arm 5that a part thereof is opposite to the detector 8 both in the openposition O and also in the closed position G and the scale 9 cannot bepivoted out of the “field of vision” of the detector 8.

The position code is preferably an absolute position code.Alternatively, the position code is an incremental code. In absoluteposition sensors 10, 10′, a position can be associated directly withevery relative location of read head 8 to scale 9 (which is related to apreviously defined null position), in that the scale 9 has an absoluteposition code made of unique code words over the entire measurementdistance, which can be associated with precisely one position by acontrol and analysis unit. In position encoders 10, 10′ havingincremental determination of positions, in contrast, the scanningsignals are not unique, but rather repeat multiple times over the entiremeasurement range. The distance to which an increment corresponds isstored in a control and analysis unit of the encoder. The distance whichis covered during a relative movement of scale 9 and read head 8 cantherefore be saved, and a relative position can thus be determined bycounting the increments. To locate such a relative position in anabsolute manner, in the case of a relative movement, one proceeds from adefined null position as an absolute reference point. Such a nullposition or null point is defined, for example, by a position referencemarker, which is detected by the read head 8, on the scale 9 (or in thecase of a stationary scale 9 on the read head 8). Sensors 10, 10′ havingincremental determination of translation locations or angles thereforehave the disadvantage that in the event of a restart of the measurementsystem, one has to proceed each time from a null or reference position.In contrast, absolute linear or angle encoders generate uniquedifferentiable scanning signals for each relative location of the partswhich can be translated or rotated in relation to one another. A uniquelinear position and/or a unique angle can thus be associated directlywith a respective relative location, i.e., without approaching areference or starting position.

The second position sensor 10′ designed as an angle encoder also has ascale 9′, having an absolute or incremental angle coding, which isscanned by a read head 8′, and therefore an item of information can beobtained about the angle position of the arm 5 and thus of the valveplate 4. In the example, the scale 9′ extends at least partially aroundthe arm 5 (at least enough that the circumference of the rotationalmovement Br is covered thereby), and therefore it is rotatable with thearm 5 in relation to the stationary detector 8′ or the entire stationarypart of the valve 1.

By means of the first and second position sensor 10, 10′, the locationof the movable parts of the valve 1, in particular the valve plate 4,and thus the state of the vacuum valve 1, in particular with respect togas-tightness and/or required reliability of the gas-tight closingcapability, can thus advantageously be monitored and evaluated in anongoing manner.

Alternatively to a pendulum valve 1 as shown, the vacuum valve 1according to the invention can be implemented using another vacuum valvetype, for example, a flap valve, slide valve, or a so-called butterflycontrol valve. Furthermore, pendulum valves are also usable, the closureof which can only be adjusted in one direction.

FIGS. 5 a and 5 b schematically show a further possible position sensorarrangement in transfer valves according to the invention, illustratedin a closed position G (FIG. 5 a ) and an open position O (FIG. 5 b ).In the figures shown, the valve seat 3 is formed on a housing 24 of thevacuum valve 1. However, it is clear to a person skilled in the art thatthe following description is applicable essentially similarly toembodiments, wherein the valve seat is provided by a process chamber,i.e., a chamber housing.

Furthermore, it is apparent that the valve mechanism, which isillustrated here solely schematically as a tilt mechanism, is not to beunderstood as restrictive and a person skilled in the art can transferthe sensor arrangement according to the invention in a similar manner,for example, to an arbitrary L-motion drive, for example, an L-motiondrive having two linear adjustment directions of the valve plateperpendicular to one another.

For the monitored guiding of the adjustment arm 5, the vacuum valve 1has here, for example, a guide component 15, wherein the drive unit 7and the guide component 15 are each in a fixed arrangement in relationto one another, here, for example, in that both the drive unit 7 andalso the guide component 15 are each connected fixed in place to thevalve housing 24. The adjustment arm 5 is furthermore mechanicallycoupled to the valve closure 4 and the drive unit 7, wherein byadjusting the valve arm 5 by means of the drive unit 7, the valveclosure 4 is adjustable between the open position O and the closedposition G essentially parallel to the valve seat, in particular in anL-motion movement as described in FIG. 3 a to 3 c.

According to the invention, the guide component has a position sensor10. The position sensor 10 is designed in this case such that both the“vertical” component V of the movement of the arm 5 and/or the valveplate 4 can be measured, and also the “horizontal” component H thereof.The position sensor 10 has a rotary encoder for this purpose, forexample, which is used both for determining the tilt position of the arm5 (i.e., the “horizontal” component) and also its linear translation, inthat it is converted beforehand into a rotational movement.Alternatively to the illustration, two separate position sensors areused and/or the position sensor or sensors are arranged at another pointin the valve, for example, on the drive 7.

FIGS. 6 a and 6 b show, similarly to FIGS. 5 a, 5 b , a further possibleembodiment of a vacuum valve 1 according to the invention. In contrastto the embodiment according to FIGS. 5 a, 5 b , the position sensor 10for measuring the position of the valve closure 4 and/or the adjustmentelement 5 is designed here as a system having an illumination means 16,for example, an LED, for illuminating the rear end of the adjustment arm5 and a camera system 17 for acquiring illumination radiation reflectedfrom the adjustment arm 5. The camera system 17 has, for example, aposition-sensitive detector, and therefore a position of the adjustmentarm 5 can be concluded from radiation reflected from the incidenceposition onto the detector. Alternatively, for example, a generation ofan image by means of the acquired radiation and an image analysis areperformed, such that a position is determinable therefrom. Camera-basedposition determinations are known in principle from the prior art. Theuse of a pattern which can be optically acquired to improve imagingposition determination is also known. Accordingly—as shown—the rear endof the adjustment element 5 has such an optical pattern 18. The“horizontal” position of the adjustment element 5 can be concluded fromthe position of the pattern 18 in the camera image, and its “vertical”position (distance to the camera) can be concluded from the imaged sizeof the image pattern, or from parts thereof (in comparison to a storedreference variable).

It is obvious that these illustrated figures only schematicallyillustrate possible exemplary embodiments. The various approaches canalso be combined with one another and with methods and devices of theprior art.

1. A vacuum valve, including a vacuum slide valve, pendulum valve, ormonovalve, for a regulation of a volume or mass flow and/or for agas-tight interruption of a flow path, comprising: a valve seat, whichhas a valve opening defining an opening axis and a first sealing surfacecircumferential around the valve opening, a valve closure for theregulation of the volume or mass flow and/or for the interruption of theflow path, comprising a second sealing surface corresponding to thefirst sealing surface; a drive unit coupled to the valve closure,comprising at least one movable adjustment element, wherein the driveunit is configured to execute an adjustment movement, such that thevalve closure is movable to and from an open position, in which thevalve closure and the valve seat are provided without contact inrelation to one another, and a closed position, in which an axiallysealing contact with respect to the opening axis exists between thefirst sealing surface and the second sealing surface, via a seal, andthe valve opening is thus closed gas-tight, wherein the vacuum valvefurther comprises at least one position sensor, wherein the at least oneposition sensor is arranged in the vacuum valve such that, in an ongoingmanner, a position of the valve closure or the at least one movableadjustment element is measurable with respect to a null position, theopen position, or the closed position, and wherein at least one of thefollowing is satisfied, including: the at least one position sensorbeing arranged in the vacuum valve such that a position measurement isperformed via the at least one position sensor with respect to at leasttwo adjustment directions of the valve closure essentially orthogonal toone another, or the at least one position sensor including at least twoposition sensors, which are arranged in the vacuum valve such that aposition with respect to a first adjustment direction is measurable by afirst position sensor and a position with respect to a second adjustmentdirection is measurable by a second position sensor, the firstadjustment direction and the second adjustment direction beingessentially orthogonal to one another.
 2. The vacuum valve according toclaim 1, wherein the at least one position sensor is arranged in thevacuum valve such that a time curve of at least a part of the adjustmentmovement is determinable, such that at least one velocity of theadjustment movement is determinable for at least one time span of theadjustment movement.
 3. The vacuum valve according to claim 1, whereinthe at least one position sensor includes a displacement sensor, adistance sensor, or an absolute position sensor.
 4. The vacuum valveaccording to claim 1, wherein the adjustment movement comprises at leastan essentially linear adjustment movement, and the at least one positionsensor is arranged to acquire at least a part of the linear adjustmentmovement, wherein the at least one position sensor includes a linearencoder.
 5. The vacuum valve according to claim 1, wherein theadjustment movement comprises at least an essentially rotationaladjustment movement, and the at least one position sensor is arranged toacquire at least a part of the rotational adjustment movement, whereinthe at least one position sensor includes an angle encoder.
 6. Thevacuum valve according to claim 1, wherein the at least one positionsensor includes an inductive position sensor, an optical positionsensor, a magnetic position sensor, a magnetostrictive position sensor,a potentiometric position sensor, or a capacitive position sensor. 7.The vacuum valve according to claim 1, wherein the at least one positionsensor is arranged outside a vacuum range separated from an externalenvironment by the vacuum valve in a defined manner.
 8. The vacuum valveaccording to claim 1, wherein the valve seat is formed by a part of thevacuum valve connected structurally to the vacuum valve, wherein thevalve seat is formed on a housing of the vacuum valve, or is provided bya process chamber or a chamber housing.
 9. The vacuum valve according toclaim 1, further comprises a processing unit that processes an acquiredposition sensor measurement signal, and wherein an item of stateinformation of the vacuum valve is ascertained based on the acquiredmeasurement signal.
 10. The vacuum valve according to claim 9, whereinthe item of state information is provided with respect to a mechanicaland/or structural integrity of the valve closure or the at least onemovable adjustment element, wherein the item of state information isascertained based on an actual-setpoint comparison for the acquiredmeasurement signal.
 11. The vacuum valve according to claim 9, whereinbased on a comparison of the item of state information to predefinedtolerance values, an output signal is provided with respect to anevaluation of a process controlled by the vacuum valve.
 12. The vacuumvalve according to claim 1, further comprising: a processing unitconfigured to determine appearance of wear of the first sealing surfaceor the second sealing surface based on position measurements from the atleast one position sensor, and output a signal based on the determinedappearance of wear.
 13. A method for monitoring a vacuum valve,including a vacuum slide valve, pendulum valve, or monovalve,regulating, via the vacuum valve, a volume or mass flow and/or for agas-tight interruption of a flow path, the vacuum valve having a valveseat, which has a valve opening defining an opening axis and a firstsealing surface circumferential around the valve opening, a valveclosure comprising a second sealing surface corresponding to the firstsealing surface, and a drive unit coupled to the valve closure,comprising at least one movable adjustment element; executing, via thedrive unit, an adjustment movement, such that the valve closure beingmovable to and from an open position, in which the valve closure and thevalve seat are provided without contact in relation to one another, anda closed position, in which an axially sealing contact with respect tothe opening axis exists between the first sealing surface and the secondsealing surface, via a seal, and the valve opening is thus closedgas-tight; measuring, via at least one position sensor, a position ofthe valve closure in an ongoing manner, position measurements areperformed regarding at least two adjustment directions essentiallyorthogonal to one another, and regarding an absolute position of thevalve closure or regarding the at least one movable adjustment elementwith respect to a null position, the open position, or the closedposition; and processing, via a processing and control unit, to monitorthe vacuum valve based on the measured position.
 14. The methodaccording to claim 13, further comprising: ascertaining an item of stateinformation of the vacuum valve, with respect to a mechanical orstructural integrity of the valve closure or the at least one movableadjustment element, based on the position measurements, wherein the itemof state information is ascertained based on an actual-setpointcomparison for the position measurements or based on a comparison of theitem of state information to predefined tolerance values; and outputtingan output signal with respect to an evaluation of a process controlledby the vacuum valve.
 15. The method according to claim 13, furthercomprising: determining, based on the position measurements, anadjustment velocity of the valve closure or the at least one movableadjustment element at least for a part of the adjustment movement, or aduration of the adjustment movement from the open position to the closedposition or vice versa.
 16. The method according to claim 13, furthercomprising: performing, by the processing and control unit based on theposition measurements, a detection of: an end location, the openposition, or the closed position of the valve closure or the at leastone movable adjustment element, a possible impact of the first sealingsurface and the second sealing surface on one another in a scope of theadjustment movement, or a possible adhesion of the first sealing surfaceand the second sealing surface on one another.
 17. A non-transitorymachine-readable medium storing a computer program which, when beingexecuted by a control and processing unit of a vacuum valve, causes thevacuum valve to perform a method comprising: regulating, via the vacuumvalve, a volume or mass flow and/or for a gas-tight interruption of aflow path, the vacuum valve having a valve seat, which has a valveopening defining an opening axis and a first sealing surfacecircumferential around the valve opening, a valve closure comprising asecond sealing surface corresponding to the first sealing surface, and adrive unit coupled to the valve closure, comprising at least one movableadjustment element; executing, via the drive unit, an adjustmentmovement, such that the valve closure being movable to and from an openposition, in which the valve closure and the valve seat are providedwithout contact in relation to one another, and a closed position, inwhich an axially sealing contact with respect to the opening axis existsbetween the first sealing surface and the second sealing surface, via aseal, and the valve opening is thus closed gas-tight; measuring, via atleast one position sensor, a position of the valve closure in an ongoingmanner, position measurements are performed regarding at least twoadjustment directions essentially orthogonal to one another, andregarding an absolute position of the valve closure or regarding the atleast one movable adjustment element with respect to a null position,the open position, or the closed position; and monitoring the vacuumvalve based on the measured position.